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Use of Enhanced Surveillance for Hepatitis C Virus Infection
to Detect a Cluster Among Young Injection-Drug Users --- New York, November
2004--April 2007

Infection with hepatitis C virus (HCV) is a leading cause of chronic liver disease in the United States
(1). Chronic hepatitis B and C virus infections were added to the
nationally notifiable diseases list in 2003
(2). Approximately 3.2 million persons in the United States have chronic HCV infection
(3). The most common risk factor for HCV infection
is illicit drug use (specifically injection-drug use [IDU])
(3,4), although approximately one third to one half of cases
have no identified risk factor (4; New York State Department of Health [NYSDOH], unpublished data, 2008).
Because approximately 80% of acute HCV infections are asymptomatic and no serologic markers for recent infection
exist, distinguishing recent from distant infection based on serology alone is challenging
(5) and establishment of national HCV infection incidence is difficult. CDC provides funding to enhance surveillance for HCV infection and other
forms of viral hepatitis in New York State (NYS) and seven other areas. One project of enhanced surveillance is to
identify those HCV infections most likely to have been acquired recently. Since January 2006, NYSDOH has prioritized
follow-up of positive laboratory markers for HCV infection among persons aged <30 years because they are more likely to
be newly infected than older persons (6). In February 2007, NYSDOH detected a cluster of HCV infections
among persons in this age group by using the prioritized algorithm. This report describes the subsequent investigation
by NYSDOH and the Erie County Department of Health (ECDOH), which identified a group of patients with histories
of IDU who were linked through a single high school that all the patients had attended at some time. The
findings demonstrate how targeted enhanced surveillance can effectively detect clusters and outbreaks and guide
appropriate interventions.

In 2004, the enhanced viral hepatitis surveillance project was launched in 34 of the 57 NYS counties outside of
New York City. Detection and follow-up of reports of newly identified persons with HCV infections among NYS residents
are given high priority to 1) collect accurate risk factor data, 2) guide prevention efforts, and 3) ensure patient referral
to appropriate treatment. NYSDOH hepatitis surveillance staff members prioritize for immediate investigation any
positive laboratory reports for markers of HCV infection among persons aged <30 years. Each week, the NYSDOH
Electronic Clinical Laboratory Reporting System generates databases containing any HCV-positive laboratory reports for
persons aged <30 years; these data are then sent to local health departments. Investigation is conducted by local
health department staff members with NYSDOH assistance and includes complete laboratory results collection,
health-care provider interview, medical record review, and patient interview.

In February 2007, NYSDOH staff members noticed an apparent high number of newly identified HCV
infections among persons aged <30 years who resided in the same postal code (postal code A), corresponding to a
suburban community of Buffalo, New York. An initial retrospective review found eight cases dating back to May 2006 in
persons who resided in postal code A (case numbers 11--18)
(Table), one of which was in a patient who had acute hepatitis
C (7). All but one of the eight initially identified cases were in persons who reported a history of IDU. Further analysis
of cases in persons residing in postal code A indicated that during November 2004--April 2007, a total of 20
HCV-positive persons aged <30 years had been reported. Fifteen of the 20 cases were diagnosed in 2006 or 2007.
The community (2000 population: 42,000) in which postal code A is located is part of Erie County and had 47.5
new reports of HCV infection per 100,000 population aged <30 years during November 2004--April 2007. During
the same period, Erie County had 18.6 new reports of HCV infection per 100,000 population; two suburban postal
codes with similar populations, socioeconomic composition, and proximity to the inner city as the investigated
community had 7.0 and 4.9 new reports of HCV infection per 100,000 population, respectively. Because the incidence of
new
reports in the community per population appeared to be approximately twice that of the county and approximately
six times greater than that of any similar suburb, further investigation to characterize the cluster was warranted.

With initial detection of the cluster, an epidemiologic investigation was launched by NYSDOH in collaboration
with ECDOH. Patients were interviewed in person by a two-person team at various locales, including correctional
facilities, rehabilitation clinics, patient residences, and other locations. Current CDC case definitions for acute and
chronic hepatitis C were used.* Four (20%) of the 20
patients had evidence of elevated serum alanine transaminase levels
and discrete symptom onset and were classified as having acute hepatitis C. Sixteen (80%) other patients were
asymptomatic or had illness that did not meet the acute case definition and were classified as having chronic HCV infection.
Median age of the 20 patients was 19 years (range: 17--29 years), all were white, 15 (75%) were male, and 19 (95%) reported
a history of IDU. Nineteen (95%) of the 20 patients attended or had attended one of the two high schools in postal
code A (high school A) (Table). Fourteen (70%) had evidence of viremia by polymerase chain reaction; three (21%) of
these 14 had a viral genotype reported. NYSDOH and ECDOH staff members successfully interviewed 11 of the 20
patients (one with acute hepatitis C and 10 with chronic HCV infection) using an integrated interview tool and a
chart abstraction tool developed for this investigation; the remaining nine
patients could not be contacted.

At the time of interview, all of the 11 interviewed
patients were aware that they had tested HCV positive.
However, three (27%) of the patients interviewed believed that their test results were false and that they were no longer (or
never were) HCV infected. Ten (91%) interviewed patients
reported previous but not current IDU (including use of
heroin, cocaine, loritabs, oxycodin, morphine, valium, or crack cocaine) and sharing of drug-use equipment; some
patients shared equipment with other identified patients. All 10 patients reported purchasing heroin in the same
inner-city Buffalo location. Noninjectable-drug use,
reported by 10 (91%) patients, was initiated at a median age of 14
years (range: 9--17 years); IDU was initiated at a median age of 16.5 years (range: 14--26 years).

At least four partnerships involving drug equipment sharing and high-risk sexual activity were reported among the
20 patients. The members of these partnerships knew other members who had experienced symptoms consistent with
acute hepatitis, such as jaundice. However, documented HCV
infection in these members, as evidenced by a report in
the NYSDOH Chronic Hepatitis Registry, could not be verified.

Among interviewed patients, median reported number of lifetime sex partners was 10 (range: four to 100). Six
(54%) patients claimed they had private health insurance, two reported having Medicaid, and three reported that they had
no health insurance. Seven of the interviewed patients reported having a primary-care physician; four of these seven
reported seeing a specialist for their HCV infection. None of the interviewed patients had received HCV treatment.
Several barriers to potential treatment were cited, including concerns regarding the side effects of medication, lack
of information regarding the availability of treatment services, lack of health insurance reimbursement, and a perceived
lack of health-care providers capable or willing to treat HCV in patients with comorbidities such as IDU or mental
health issues.

Several initiatives were launched by NYSDOH and ECDOH throughout Erie County to address the
apparent clustering of HCV infection among injection-drug users. Staff members from NYSDOH, the NYS Office of
Alcoholism and Substance Abuse Services, and ECDOH conducted cross-training sessions and developed a resource manual to
help identify primary care, sexually transmitted disease (STD)/human immunodeficiency virus (HIV) screening,
drug treatment, harm reduction, and HCV treatment services for patients. All interviewed patients were referred to
ECDOH counselors for HIV/acquired immunodeficiency syndrome (AIDS) risk assessment and personalized
intervention development. ECDOH conducted multiple events held at various community locations and ECDOH clinics,
offering HCV, HIV, and STD screening, referral for services, and education on prevention, risk
reduction, and family planning; these services are ongoing at all five ECDOH clinics. Presentations on hepatitis epidemiology, diagnosis and testing,
and prevention were conducted at medical practices that serve high-risk communities throughout Erie County. ECDOH
also collaborated with the Erie County Department of Mental Health to integrate HCV messages into existing
prevention programs and implement screening programs in target areas with high HCV infection rates. Finally, ECDOH
worked with school district representatives and high schools to address prevention of IDU and HCV transmission.

Editorial Note:

One goal of the CDC-funded enhanced viral hepatitis surveillance protocols is high-priority
follow-up of cases that are likely to represent acute HCV infection. Another goal is detection of clusters or outbreaks of such
cases, as this report describes. The markedly elevated number of new reports of HCV infection per population detected
among persons aged <30 years in postal code A, compared with the number of reports in the surrounding
community, indicated an apparent cluster of recently
infected patients. Nearly all of the identified patients in the cluster reported
a history of IDU, and partnerships involving drug equipment sharing, which have been
described previously (8), were identified among the cluster. The cause of this cluster likely was IDU with shared, inadequately cleaned
equipment. Because the investigation targeted only cases in persons aged <30 years, more direct links among members of this
cluster involving persons aged >30 years might exist within the community. Furthermore, although infections identified
in persons aged <30 years are more likely to be new infections than those identified in persons aged
>30 years, not all infections in the population aged <30 years are new; a portion of the patients in this cluster likely had been
infected with HCV for years.

Although the number of new reports of HCV infection per population in postal code A was higher than the
overall Erie County number during November 2004--April 2007, this analysis could not determine whether this
elevated number of reports represented a previously established and ongoing higher rate of HCV infection among persons
aged <30 years or a more recent phenomenon. Cases within this apparent cluster likely are a reflection of the ongoing
HCV epidemic among injection-drug users in the United States
(9). Ongoing educational efforts and increased
public awareness of hepatitis C, particularly among injection-drug users, might have led to higher rates of testing,
which yielded additional reports. Because the prioritized algorithm was not in place before January 2006, earlier reported
cases of HCV infection among this population might have gone unrecognized. Continued enhanced surveillance is needed
to complement routine surveillance for HCV infections to better understand the burden of hepatitis C and to identify
and prevent new HCV infections.

The results of this investigation demonstrate the potential for improved and consistent national hepatitis
C surveillance to identify cases for investigation, estimate the magnitude of HCV infection and disease, detect
outbreaks, evaluate response measures, and facilitate research to initiate appropriate prevention measures. Given limited
resources, an enhanced surveillance approach to give highest priority to likely new cases of HCV infection, such as those in
persons aged <30 years, can be implemented to identify clusters and outbreaks. Establishing effective systems that
provide reliable data to detect HCV infections among all populations could have a lasting effect on HCV disease control.

Acknowledgments

This report is based, in part, on contributions by C Moore, Erie County Dept of Health; L Isabella, K Kufel, R Furlani, I Jones, New
York State Dept of Health.

References

Rustgi VK. The epidemiology of hepatitis C infection in the United States. J Gastroenterol 2007;42:513--21.

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